I bought a NHT SubOne, which was sold as being in good working condition. Unfortunately, one of the output transistors is shorted so I suspect high DC levels were sent to the driver until the fuse blew.

The driver gives a somewhat decent-looking impedance curve and I don't hear any rubbing or buzzing, but the impedance peak was very low and the driver seemed "floppy".

As I explored a bit more, I discovered the glue joint between the cone, spider, and former isn't full securing the spider. As I push out on the cone, I will reach a certain point where the spider "pops" out a bit. When I release the cone, and the driver is at rest, you cannot see any damage. So, I am hoping I can fix the driver. Does this explain the situation or are pictures required?

I found some threads about transducer repair, but nothing that answered this question about the specific type of glue/epoxy that should be used in this situation. It does appear there are some individuals who are very experienced with transducers so I think this is the right place to get this information

But what glue should I use? I assume epoxy is the right choice, but what kind? There is epoxy for plastics - would that be right? If the spider has resin in it, and I'm epoxying to an existing glue bead, I would think epoxy for plastics would be the right choice. But is there something better? Will the 5 min stuff be OK, or should I search out the 20 min, 30 min, 60 min, etc. type of epoxy.

My plan is to push out the cone and then inject epoxy into the "joint" using a syringe or some other tool with a long snout. Are there any better ideas for applying the glue/epoxy?

It is going to be very difficult to repair the "triple joint" on assembled driver, the problem is going to be making sure that everything is aligned properly while the epoxy sets. You can search for the catalyzed glue that speaker manuf. use, but I've had good luck with the 20 minute two-part epoxy. A very experienced speaker designer/manuf. suggested I try it and it has worked on some high-output drivers.

Actually, all the parts hold together in the proper place when the driver is at rest. It's only when the cone is moved that you can see where the glue has stopped holding the "ring" of the spider. The innermost part of the spider is still glued and stays where it should be. So if I get the right adhesive in there, I think I should be in good shape.

20 min epoxy it is. What type of epoxy since they make various "flavors"? Should I go for the epoxy for plastics?

In standard hobby store epoxies (like Bob Smith brand), the 20 minute version is a finish cure resin. It's thinner for a smooth texture and wicks into crevices well, with a good balance between short curing time and enough working time before it sets.

Not quite the same consistency as hardware store epoxies, unless it's one marketed for use with fiberglass cloth.

takes heat and is a viscose liquid very popular speaker adhesive with makers,also used bnd disk break pads very rugid. Get a bottle of accelerator with the glue but don't breath the fumes when liquid nasty stuff.